speedo problems

i had swappd the front sprocket to a 15 tooth and it messed up the speedo. i put the factory sprocket back on in hopes to correct it but it is still not reading. what is the problem and will it correct itself ? also my "FI" light is coming on after a few minutes of riding, is this caused by the malfunctioning speedo? any help would be appreciated. thanks, cameron

 

Most new bikes now have digital speedos, the pickup for the electronic signal can usually be found on the front sprocket cover. The pickup unit counts the number of rotations of the front sprocket and with a pre-programmed calculation in the bikes computer or instrument console is able to give a speed reeding. There is a white cap on the inside of the sprocket cover that fits over the nut that tightens the sprocket to the shaft. The nut actually drives the electronic device on the cover which inturn counts the revolutions of said sprocket. Better check you haven't left something out or damaged on re-assembly. Unfortunately this device can't count to 15, however there is a device called a "speedo healer" which not only adjust the reading according to your final drive ratio, but can also be used to correct factory speedo error. Try Australian Motorcycle Components info@amcmotorcycles.com or www.amcmotorcycles.com Goodluck, waynej

 

Interesting to see someone else having speedo problems. I have an 02 VFR and just replaced the chain, front sprocket and rear sprocket ( changed to a 45 from a 43 tooth ). While the bike runs great and the high gear roll on is noticeably improved my speedo now fluctuates up and down constantly. I estimate the variance to be between 10 to 15 KMph. I visually checked the speed sensor and it seems to be fine. The dealer suggested I try disconnecting the battery and reconnecting it to see if that might reset the speedo. I just took the bike out for a ride and it is still acting up. I will try the website you mentioned to see if that might offer a resolve as I expected that changing the rear sprocket would likely affect the accuracy of the speedo...thanks.

 

I had the same problem with my '99. While the sensor appeared to be in the right place, the spacer behind the front sprocket cover had moved during reassembly and was not allowing the white cap of the sensor to engage properly with the sprocket nut. Disassembly and careful reassembly were all that were needed to fix this annoying problem (speedo flutter).

 

Thanks for the advice, I'll check that spacer on mine tomorrow.

 

Well, I discovered that the problem had to do with the aftermarket sprocket. It is slightly narrower than the stock sprocket. When the sprocket bolt is tightened it draws the bolt in deeper and away from the speed sensor so that the two barely make contact which caused the eratic readings. Adding two washers to the bolt solved the problem!